Noise suppressing baffle discharge exit

ABSTRACT

A baffle, which is used in a discharge duct which removes material tangentially from a device with rotating blades such as a vertical shaft refiner or centrifuge, suppresses noise of the device and limits the product buildup on the walls of the duct. The baffle has a portion blocking part of the opening between the device and the duct with a second portion extending along the duct providing a change in the cross-section of the duct adjacent the opening. Due to the change in the cross-section caused by the baffle, material being discharged into the duct expands with a corresponding decrease in its velocity of travel to eliminate or reduce the tendency of the material to stick to the side wall of the duct to cause a product buildup.

United States Patent Prew et al.

[4 1 Aug. 29, 1972 [54] NOISE SUPPRESSING BAFFLE DISCHARGE EXIT [73]Assignee: Beloit Corporation, Beloit, Wis.

[22] Filed: Nov. 19, 1969 21 Appl. No: 877,888

[52] US. Cl. ..233/46, 415/204, 138/39 [51] Int. Cl. ..B04b 11/00 [58]Field of Search .233/1, 16, 27, 28, 46, 47 R;

[56] References Cited UNITED STATES PATENTS 2,956,736 10/1960 Mayer eta1 ..4l5/204 3,034,702 5/1962 Larsson et a1 ..415/204 X FOREIGN PATENTSOR APPLICATIONS 603,418 10/1934 Germany ..415/207 Primary ExaminerJordanFranklin Assistant Examiner--George H. Krizmanich Att0meyHill, Sherman,Meroni, Gross & Simpson [5 7 ABSTRACT A baffle, which is used in adischarge duct which removes material tangentially from a device withrotating blades such as a vertical shaft refiner or centrifuge,suppresses noise of the device and limits the product buildup on thewalls of the duct. The bnflle has a portion blocking part of the openingbetween the device and the duct with a second portion extending alongthe duct providing a change in the cross-section of the duct adjacentthe opening. Due to the change in the cross-section caused by thebaffle, material being discharged into the duct expands with acorresponding decrease in itsvelocity of travel to eliminate or reducethe tendency of the material to stick to the side wall of the duct tocause a product buildup.

5 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of theInvention The present invention pertains to a baffle for a dischargeduct and particularly for a baffle for a discharge duct of a tangentialoutlet for a machine havin g rotating members.

2. Prior Art When handling a material which is either moist or in aslurry, the material tends to accumulate in a product buildup at anypoint at which a change of direction of the flow of material occurs orat a point at which the flow of material is directed against a surfaceof the passageway. In a refiner having rotating blades or a centrifuge,the outlet duct is arranged to remove material from the refiner ordevice in a tangential direction. However, the size of the opening ofthe outlet duct enables a certain portion of the material being expelledtherethrough to travel in a path which is not parallel to the axis ofthe duct. This results in an accumulation or product buildup ofmaterials on the trailing wall surface of the duct which product buildupeventually chokes off or blocks the flow of materials through the duct.

Another difficulty experienced in tangential discharge ducts of a devicehaving rotating members including blades is that due to the size of theduct opening, the trailing edge or trailing wall provides a surfacewhich approaches a parallel relationship to the radius of the rotatingmembers. Such an arrangement causes excessive noise in the device due tothe blades rotating past a surface which is substantially radial withrespect to the axis of rotation.

SUMMARY OF THE INVENTION The present invention is directed to a baffledevice for an outlet duct which device reduces the noise level of themachine and reduces the buildup or accumulation on a surface of productsbeing removed through the duct. In the preferred embodiment, the baffledevice includes a portion which reduces the size of the outlet openingof the duct and which changes the crosssection of the duct adjacent tothe opening into the machine.

Accordingly it is an object of the present invention to provide a bafflein a discharge duct which suppresses noise of the machine.

Another object of the present invention is to provide a baffle in thedischarge duct of a machine having tangential removal of material whichreduces the accumulation of material on the walls of the discharge duct.

Other objects, features and advantages of this invention will be readilyapparent from the following description of the preferred embodimenttaken together in conjunction with the accompanying drawings althoughvariations and modifications may be effected without departing from thescope and spirit of the novel concepts of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan elevational view of aduct utilizing the baffles of the present invention;

FIG. 2 is a cross-section taken along lines II-II of FIG. 1; and

FIG. 3 is a view taken along the lines III--III with portions inelevation for purposes of illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENT Although the principles of thepresent invention are of utility for preventing product buildup andreducing noise for any discharge duct, the principles are particularlyuseful when incorporated in a tangential discharge duct for a machinehaving rotating members which duct is illustrated in FIG. 2 andgenerally indicated at 10.

The duct 10 is illustrated as being mounted on a housing 11 of a devicehaving a substantially cylindrical inner peripheral surface 12 defininga cylindrical chamber for receiving rotating members with blades (notillustrated). The rotating members in the housing I 1 rotate in adirection of the arrow 13 and the duct has a leading wall 14 whichextends tangentially to the periphery of the inner cylindrical surface12 of the housing 11. The duct 10 is substantially rectangular incross-section and has a trailing wall 15 which is substantially parallelto the wall 14 and a pair of parallel side walls 16 and 17 which wallsforming with the housing 11 having an opening 18 having a trailing edge24 which leads from location 25 back to location 19.

Since the trailing wall 15 is parallel to the leading wall 14, thetrailing wall 15 at location 19 is not in a tangential relationship tothe cylindrical surface 12 or to the flow of material dischargedadjacent location 19. Thus, material being discharged tangentially tothe cylindrical wall 12 at a point midway between the leading wall 14and the trailing edge or wall 15 is projected at an angle to the axis ofthe duct 10 and against the trailing wall 15 and this material tends toaccumulate on the surface of the wall 15.

Since the trailing wall 15 is parallel and spaced from the leading wall14, the trailing wall 15 forms an acute angle. As mentioned above, inusual structures heretofore available, the blade on the rotationalmember disposed in the chamber had a substantial parallel relationshipto an axially extending edge positioned at location 19 and thisrelationship increased the noise level of the machine or device.

The present invention provides a baffle means generally indicated at 21disposed in the interior of the duct 10 adjacent to the trailing wall15. As illustrated, the baffle means 21 comprises a pair of platemembers 22 and 23 with the plate member 22 being triangular inconfiguration and having a curvature which is substantially the same asthe curvature of the cylindrical surface 12 of the housing 11. The plate22 extends from the trailing location 19 of the opening 18 and blocks orcloses a portion of the opening 18 to form an effective opening. Theplate 22 has a leading edge 24 to which the second plate member 23 isjoined. As illustrated, the second plate member 23 extends from theleading edge 24 of the curved plate member 22 and extends at an angle toan axis of the duct 10 to merge or be attached to the trailing wall 15and a side wall 16 of the duct 10. The position of the plate member 23in the duct 10 causes a reduction in the cross-sectional area of theduct 10 adjacent the opening 18 and the amount of the reduction ofcross-sectional area gradually decreases as the distance along the duct10 from the opening 18 decreases. The position and the configuration ofthe baffle means 21 restricts the size of an opening 18 and causes agradual change of the cross-sectional area of the duct adjacent theopening 18. Thus materials expelled through the opening 18 into the duct10 gradually expands with a decrease in the velocity which is beneficialand removes one of the causes for a buildup or accumulation of theproduct on the walls of the duct. Also, the configuration and positionof the plate member 23 decreases the angle of incidence which materialdischarged tangentially to the opening into the duct 10 strikes asurface of the duct and reduces the tendency for the material to stickor adhere to the wall surfaces. The position of the plate 22 alsochanges the efiective relationship of the trailing wall surface to thepassing blades of the rotating member and causes a reduction orsuppression in the noise level of the device.

In the preferred embodiment and best illustrated in FIG. 3, the bafflemeans 21 is disposed with the leading edge 24 of the plate member 22extending across the opening 18 at an acute angle to the plane which isperpendicular to the axis of rotation of the rotating members and bladesin the housing 11 and to the axis of the cylindrical inner peripheralsurface 12 which planes are substantially parallel to walls 16 and 17.Due to this disposition, the effective opening formed by the plate 22 inthe opening 13 has its maximum size adjacent to the leading wall 14,which forms a leading edge of the opening and is gradually reducedstarting at point as the arcuate distance from the wall 14 toward thetrailing edge 19 increases. In other words, the leading edge 24 of theplate member 22 may also be called the trailing edge of the effectiveopening of the housing with respect to the direction (arrow 13) ofmovement of the rotating blade member. Thus, the plate 22 reduces theamount of material being discharged tangentially from the chamber formedby the cylindrical surface 12 as the blades move past point 25. Such areduction of material causes a reduction in the amount of material whichtends to be deposited on the wall surface 15. As illustrated, the member23 is triangular in configuration and has a leading edge attached to theleading edge 24 of the member 22 and the remaining two edges attached tothe side wall 16 and trailing wall 15 respectively. The plate member 23preferably fiat or planar and the remaining two edges define a point 26which is disposed in a corner 27 between the walls 15 and 16.

As mentioned hereinabove, the noise level increases in the machine whenthe blades and the trailing edge wall of a duct approaches a parallelconfiguration. With the addition of the baffle means 21, the angle ofthe trailing wall surface or its effective configuration caused by theplate 23 is closer to a tangential relationship with the blade as theblade moves across the opening towards the trailing edge 19. Thus, thebaffle 21 removes the relationship of the trailing edge wall and theblades which causes the excessive noise in the system and provide arelationship between the trailing wall surface and blades that promotenoise suppression.

As illustrated, the duct 10 has a substantially rectangularcross-section and the provisions of the baffle means 21 changes theeffective shape of the opening 18 of the duct into the chamber formed bythe cylindrical surface 12 to be substantially trapezoidal. A bafflemeans similar to means 21 could be utilized with a duct having acircular cross-section with appropriate changes in the configuration orshape of the plate 22 to provide for closing a portion of thesubstantially circular opening and in the plate 23 for attachment of theupper edge to a curved surface of the circular duct.

The baffle means 21 reduces the tendency of product buildup on the wallsof the duct by changing the configuration of the opening, by providing agradual increase in the cross-sectional area of the duct with acorresponding decrease in the velocity of the product being dischargedthrough the duct 10, and by changing the angle of incidence of materialstriking a surface of the duct as the material travels tangentiallythrough the opening 18 to reduce the tendency of sticking to a surfaceof the duct. The baffle means 21 also suppresses noise in the device bychanging'the configuration and relationship of the trailing surface ofthe duct that the blades move past.

Although minor modifications might be suggested by those versed in theart, it should be understood that we wish to embody within the scope ofthe patent warranted hereon all such modifications as reasonably andproperly come within the scope of our contribution to the art.

We claim as our invention:

1. In a device having a housing with a substantially cylindrical innerperiphery for receiving a rotating member and a tangential dischargeduct forming a discharge opening for said housing, the improvementcomprising means reducing the buildup of products removed through saidduct on the wall surfaces thereof and reducing the noise of theoperation of said device, said means including a baffle member disposedin said opening to block a portion thereof, said baffle member includinga first surface closing a portion of the opening forming an effectiveopening and a second surface extending from said first surface alongsaid duct, said second surface extending from a leading edge, of thefirst surface at an angle to the axis of the duct and merging with thewall of said duct forming a cross-sectional area of the duct whichincreases along the duct from said effective opening, the leading edgeof said second surface forming an acute angle with a plane extendingperpendicular to the axis of the cylindrical inner periphery of thehousing.

2. In a device constructed in accordance with claim 1 wherein saiddischarge duct is rectangular in shape and wherein said second surfaceis triangular in shape and is disposed in a corner of said duct at saiddischarge opening with its leading edge causing the effective opening tobe trapezoidal in shape.

3. In a device constructed in accordance with claim 1 wherein said firstand second surfaces are formed by plates mounted in the dischargeopening.

4. in a device constructed in accordance with claim 1 wherein thecross-sectional area of the discharge duct increases outwardly of theopening with the direction of the increase in the area extending towardone side of the housing.

5. in a device constructed in accordance with claim 1 wherein saidsurfaces are formed by plates with the plate forming the first surfacehaving a curvature substantially the same as the curvature of thecylindrical inner periphery of the housing.

1. In a device having a housing with a substantially cylindrical innerperiphery for receiving a rotating member and a tangential dischargeduct forming a discharge opening for said housing, the improvementcomprising means reducing the buildup of products removed through saidduct on the wall surfaces thereof and reducing the noise of theoperation of said device, said means including a baffle member disposedin said opening to block a portion thereof, said baffle member includinga first surface closing a portion of the opening forming an effectiveopening and a second surface extending from said first surface alongsaid duct, said second surface extending from a leading edge of thefirst surface at an angle to the axis of the duct and merging with thewall of said duct forming a cross-sectional area of the duct whichincreases along the duct from said effective opening, the leading edgeof said second surface forming an acute angle with a plane extendingperpendicular to the axis of the cylindrical inner periphery of thehousing.
 2. In a device constructed in accordance with claim 1 whereinsaid discharge duct is rectangular in shape and wherein said secondsurface is triangular in shape and is disposed in a corner of said ductat said discharge opening with its leading edge causing the effectiveopening to be trapezoidal in shape.
 3. In a device constructed inaccordance with claim 1 wherein said first and second surfaces areformed by plates mounted in the discharge opening.
 4. In a deviceconstructed in accordance with claim 1 wherein the cross-sectional areaof the discharge duct increases outwardly of the opening with thedirection of the increase in the area extending toward one side of thehousing.
 5. In a device constructed in accordance with claim 1 whereinsaid surfaces are formed by plates with the plate forming the firstsurface having a curvature substantially the same as the curvature ofthe cylindrical inner periphery of the housing.